In an announcement this morning, Olympus and Panasonic have revealed details about a joint venture that has the potential, at least, to change the advanced compact camera landscape forever: the Micro Four Thirds open format lens mount and sensor standards.

The two companies have previously partnered to produce SLR cameras using the Four Thirds lens mount and imager – employing a sensor that’s smaller than the APS-C or full-frame types found in most DSLRs, but still significantly larger than the sensors currently available in compact cameras. Logically, the name itself comes from the system sensor’s aspect ratio: 4:3, versus the 3:2 aspect ratio seen in larger DSLR sensors.

The appeal of the original Four Thirds system was twofold: most notably, a physically smaller sensor makes it possible to develop camera bodies and lenses and lenses that are more compact than those from other manufacturers using conventional larger sensor sizes. Likewise, Four Thirds is an open format, providing some degree of compatibility among lenses from the manufacturers (Panasonic, Leica, Olympus, and Sigma at the moment) currently designing Four Thirds optics.

How is Micro Four Thirds different?

Micro Four Thirds looks to utilize the same sensor size and technologies (i.e. Olympus’s “Live MOS” imager) developed for the original Four Thirds system. Differences between the two formats come in the design of the lens mount – and as a result, in the physical size of forthcoming Micro Four Thirds camera bodies.

Fundamental design changes to the Micro Four Thirds mount when compared to the original system include a distance from lens to sensor that’s roughly half of that used in full-size Four Thirds cameras, a mount diameter that’s 6mm smaller, and an increased number of contacts for lens/body communication (in part to provide support for video shooting at some point in the future, according to the announcement). Diagrams from Four-Thirds.org, the official system website, show the difference in mount size.

Olympus already has the market cornered on tiny DSLR bodies with their compact E-420, but the combination of reduced flangeback distances as well as the elimination of the mirror and mirrorbox in proposed Micro Four Thirds cameras promises to shrink new models to a form factor not usually associated with interchangeable-lens cameras.

You read that correctly: Micro Four Thirds cameras will not be true SLR (or single-lens reflex) cameras. There’s no mirror, and thus, no reflex action.

Of course, the elimination of the mirror and related systems also means that resulting cameras will utilize live view composition only – just like a point-and-shoot, but with the flexibility of interchangeable lenses.

What about lenses?

A smaller lens mount and shorter flangeback have advantages where reducing lens size is concerned as well. According to the joint Olympus/Panasonic announcement, new lens development exclusively for Micro Four Thirds will “take advantage of significantly more compact lenses, particularly in the wide-angle and high-power zoom range.”

While only Micro Four Thirds standard lenses will provide the full range of system functions (which potentially include the ability to capture video), Four Thirds manufacturers are proposing a backward-compatible solution for using larger full Four Thirds lenses on Micro Four Thirds bodies via an adapter.

What to expect next?

As noted, today’s announcement unveiled specifics of the Micro Four Thirds standard only; no details about actual camera bodies or lenses using the new standard have yet been released. It’s a safe bet, however, that physical representatives of the technology outlined in this announcement will be on display at Photokina next month, so keep an eye out for official product launches from both Panasonic and Olympus before that time.

Finally, in providing DSLR image quality in a package that mirrors the size, weight, and LCD-only user experience of an advanced compact camera, Olympus and Panasonic look to fill a niche with the Micro Four Thirds system currently served by the likes of Canon‘s G9, Sigma’s DP1, and Panasonic‘s own LX3. With a larger sensor (and the resulting lower noise and improved image quality), Micro Four Thirds appears to address many of the fundamental concerns associated with the current crop of advanced compact cameras.

How well the actual implementation of these technologies will perform – and how system cameras will be speced and priced – is still yet to be determined, but for those who’ve been eagerly awaiting more offerings in the large-sensor compact space, the Micro Four Thirds system seems to have a lot of promise.

For complete technical details as they stand right now, visit Four-Thirds.org.